What is JSON used for in web applications?

Question

I am relatively new to web development and web applications. I have heard about JSON but am not sure exactly what its uses are.

possible duplicate of [What is JSON and why would I use it?](http://stackoverflow.com/questions/383692/what-is-json-and-why-would-i-use-it) — Nikhil Agrawal, Jan 08 '14 at 19:40

score 9 · Accepted Answer · 2011-03-04T23:37:09.150

9

JSON is a format for encoding information returned by the server. When you call a script with AJAX/XHR (e.g. with JavaScript) the returned information can come via XML, JSON, or another format. JSON is simply a way to return that data in an object structure native to JavaScript - in a way that generally doesn't require a lot of parsing, like XML does.

edited Mar 04 '11 at 23:37

answered Mar 04 '11 at 23:28

1

+1 JSON is a *subset* of JavaScript object literal notation is well suited to modeling objects composed of dictionaries, lists and primitive values -- especially JavaScript objects. A JSON parser (turns JSON into JavaScript objects, for instance) is therefor a direct transformation. XML, on the other hand, generally isn't able/used to provide this simple mapping and generally requires a conversion/extraction from the XML document or fragment. This *simplicity* is one of JSON's biggest strengths. – Mar 04 '11 at 23:40

score 4 · Answer 2 · answered Mar 04 '11 at 23:32

It is a kind of language for encoding information. For example, if you want to send information about person from one place to another, then it JSON it may look like this:

{
     "firstName": "John",
     "lastName": "Smith",
     "age": 25,
     "address":
     {
         "streetAddress": "21 2nd Street",
         "city": "New York",
         "state": "NY",
         "postalCode": "10021"
     },
     "phoneNumber":
     [
         {
           "type": "home",
           "number": "212 555-1234"
         },
         {
           "type": "fax",
           "number": "646 555-4567"
         }
     ]
 }

Taken from wiki. :) See http://en.wikipedia.org/wiki/JSON for more details.

score 1 · Answer 3 · answered Mar 04 '11 at 23:39

First, it's an acronym for JavaScript Object Notation.

It is often used in places where applications deal with object data structures (often seen in languages such as Java, C#, etc.), and associative arrays (key-value pairs seen in many languages such as Python, PHP, etc.)

To answer your question, it's a simple and efficient way to encode objects into strings, transfer them, and recreate the objects on the other end.

JSON on Wikipedia

JSON Homepage

Example of JSON encoding in PHP

What is JSON used for in web applications?

3 Answers3